. it was beeping so loud right outside your room. our results are disturbing but sleep researcher dr. gary smith says he sees this all the time. >> it would astound you how loud the sounds can get and children continue to sleep through them. >> reporter: why do kids sleep through the alarms? >> they are simply not small adults. they are different biologically. children spend more time in deep sleep than adults do. that's why it is harder for them to awaken in the case of an emergency. >> reporter: that's why he says families need an escape plan. make sure each adult has a designated child to wake up in a real fire. meanwhile researchers are trying to find a sound that works better than the beeping. dr. smith is experimenting with a new alarm prototype. it allows parents to record their own voices as the alarm telling their kids to get up. he says it seems to be working. right now these alarms aren't on the market and it could be at least another year before they are. jeff rossen, nbc news, new york. >>> as we said, this deserves our attention. you can see more of this reporting sunday night on "